text: """
  :mod:`jedi.evaluate.imports` is here to resolve import statements and return
  the modules/classes/functions/whatever, which they stand for. However there's
  not any actual importing done. This module is about finding modules in the
  filesystem. This can be quite tricky sometimes, because Python imports are not
  always that simple.
  
  This module uses imp for python up to 3.2 and importlib for python 3.3 on; the
  correct implementation is delegated to _compatibility.
  
  This module also supports import autocompletion, which means to complete
  statements like ``from datetim`` (cursor at the end would return ``datetime``).
  """
  import os
  
  from parso.python import tree
  from parso.tree import search_ancestor
  from parso import python_bytes_to_unicode
  
  from jedi._compatibility import (FileNotFoundError, ImplicitNSInfo,
                                   force_unicode, unicode)
  from jedi import debug
  from jedi import settings
  from jedi.common.utils import traverse_parents
  from jedi.parser_utils import get_cached_code_lines
  from jedi.evaluate import sys_path
  from jedi.evaluate import helpers
  from jedi.evaluate import compiled
  from jedi.evaluate import analysis
  from jedi.evaluate.utils import unite
  from jedi.evaluate.cache import evaluator_method_cache
  from jedi.evaluate.filters import AbstractNameDefinition
  from jedi.evaluate.base_context import ContextSet, NO_CONTEXTS
  
  
  class ModuleCache(object):
      def __init__(self):
          self._path_cache = {}
          self._name_cache = {}
  
      def add(self, module, name):
          path = module.py__file__()
          self._path_cache[path] = module
          self._name_cache[name] = module
  
      def iterate_modules_with_names(self):
          return self._name_cache.items()
  
      def get(self, name):
          return self._name_cache[name]
  
      def get_from_path(self, path):
          return self._path_cache[path]
  
  
  # This memoization is needed, because otherwise we will infinitely loop on
  # certain imports.
  @evaluator_method_cache(default=NO_CONTEXTS)
  def infer_import(context, tree_name, is_goto=False):
      module_context = context.get_root_context()
      import_node = search_ancestor(tree_name, 'import_name', 'import_from')
      import_path = import_node.get_path_for_name(tree_name)
      from_import_name = None
      evaluator = context.evaluator
      try:
          from_names = import_node.get_from_names()
      except AttributeError:
          # Is an import_name
          pass
      else:
          if len(from_names) + 1 == len(import_path):
              # We have to fetch the from_names part first and then check
              # if from_names exists in the modules.
              from_import_name = import_path[-1]
              import_path = from_names
  
      importer = Importer(evaluator, tuple(import_path),
                          module_context, import_node.level)
  
      types = importer.follow()
  
      #if import_node.is_nested() and not self.nested_resolve:
      #    scopes = [NestedImportModule(module, import_node)]
  
      if not types:
          return NO_CONTEXTS
  
      if from_import_name is not None:
          types = unite(
              t.py__getattribute__(
                  from_import_name,
                  name_context=context,
                  is_goto=is_goto,
                  analysis_errors=False
              )
              for t in types
          )
          if not is_goto:
              types = ContextSet.from_set(types)
  
          if not types:
              path = import_path + [from_import_name]
              importer = Importer(evaluator, tuple(path),
                                  module_context, import_node.level)
              types = importer.follow()
              # goto only accepts `Name`
              if is_goto:
                  types = set(s.name for s in types)
      else:
          # goto only accepts `Name`
          if is_goto:
              types = set(s.name for s in types)
  
      debug.dbg('after import: %s', types)
      return types
  
  
  class NestedImportModule(tree.Module):
      """
      TODO while there's no use case for nested import module right now, we might
          be able to use them for static analysis checks later on.
      """
      def __init__(self, module, nested_import):
          self._module = module
          self._nested_import = nested_import
  
      def _get_nested_import_name(self):
          """
          Generates an Import statement, that can be used to fake nested imports.
          """
          i = self._nested_import
          # This is not an existing Import statement. Therefore, set position to
          # 0 (0 is not a valid line number).
          zero = (0, 0)
          names = [unicode(name) for name in i.namespace_names[1:]]
          name = helpers.FakeName(names, self._nested_import)
          new = tree.Import(i._sub_module, zero, zero, name)
          new.parent = self._module
          debug.dbg('Generated a nested import: %s', new)
          return helpers.FakeName(str(i.namespace_names[1]), new)
  
      def __getattr__(self, name):
          return getattr(self._module, name)
  
      def __repr__(self):
          return "<%s: %s of %s>" % (self.__class__.__name__, self._module,
                                     self._nested_import)
  
  
  def _add_error(context, name, message=None):
      # Should be a name, not a string!
      if message is None:
          name_str = str(name.value) if isinstance(name, tree.Name) else name
          message = 'No module named ' + name_str
      if hasattr(name, 'parent'):
          analysis.add(context, 'import-error', name, message)
      else:
          debug.warning('ImportError without origin: ' + message)
  
  
  class ImportName(AbstractNameDefinition):
      start_pos = (1, 0)
      _level = 0
  
      def __init__(self, parent_context, string_name):
          self.parent_context = parent_context
          self.string_name = string_name
  
      def infer(self):
          return Importer(
              self.parent_context.evaluator,
              [self.string_name],
              self.parent_context,
              level=self._level,
          ).follow()
  
      def goto(self):
          return [m.name for m in self.infer()]
  
      def get_root_context(self):
          # Not sure if this is correct.
          return self.parent_context.get_root_context()
  
      @property
      def api_type(self):
          return 'module'
  
  
  class SubModuleName(ImportName):
      _level = 1
  
  
  class Importer(object):
      def __init__(self, evaluator, import_path, module_context, level=0):
          """
          An implementation similar to ``__import__``. Use `follow`
          to actually follow the imports.
  
          *level* specifies whether to use absolute or relative imports. 0 (the
          default) means only perform absolute imports. Positive values for level
          indicate the number of parent directories to search relative to the
          directory of the module calling ``__import__()`` (see PEP 328 for the
          details).
  
          :param import_path: List of namespaces (strings or Names).
          """
          debug.speed('import %s' % (import_path,))
          self._evaluator = evaluator
          self.level = level
          self.module_context = module_context
          try:
              self.file_path = module_context.py__file__()
          except AttributeError:
              # Can be None for certain compiled modules like 'builtins'.
              self.file_path = None
  
          if level:
              base = module_context.py__package__().split('.')
              if base == [''] or base == ['__main__']:
                  base = []
              if level > len(base):
                  path = module_context.py__file__()
                  if path is not None:
                      import_path = list(import_path)
                      p = path
                      for i in range(level):
                          p = os.path.dirname(p)
                      dir_name = os.path.basename(p)
                      # This is not the proper way to do relative imports. However, since
                      # Jedi cannot be sure about the entry point, we just calculate an
                      # absolute path here.
                      if dir_name:
                          # TODO those sys.modules modifications are getting
                          # really stupid. this is the 3rd time that we're using
                          # this. We should probably refactor.
                          if path.endswith(os.path.sep + 'os.py'):
                              import_path.insert(0, 'os')
                          else:
                              import_path.insert(0, dir_name)
                      else:
                          _add_error(
                              module_context, import_path[-1],
                              message='Attempted relative import beyond top-level package.'
                          )
                          import_path = []
                  # If no path is defined in the module we have no ideas where we
                  # are in the file system. Therefore we cannot know what to do.
                  # In this case we just let the path there and ignore that it's
                  # a relative path. Not sure if that's a good idea.
              else:
                  # Here we basically rewrite the level to 0.
                  base = tuple(base)
                  if level > 1:
                      base = base[:-level + 1]
  
                  import_path = base + tuple(import_path)
          self.import_path = import_path
  
      @property
      def str_import_path(self):
          """Returns the import path as pure strings instead of `Name`."""
          return tuple(
              name.value if isinstance(name, tree.Name) else name
              for name in self.import_path
          )
  
      def sys_path_with_modifications(self):
  
          sys_path_mod = (
              self._evaluator.get_sys_path()
              + sys_path.check_sys_path_modifications(self.module_context)
          )
  
          if self.import_path and self.file_path is not None \
                  and self._evaluator.environment.version_info.major == 2:
              # Python2 uses an old strange way of importing relative imports.
              sys_path_mod.append(force_unicode(os.path.dirname(self.file_path)))
  
          return sys_path_mod
  
      def follow(self):
          if not self.import_path:
              return NO_CONTEXTS
  
          return self._do_import(self.import_path, self.sys_path_with_modifications())
  
      def _do_import(self, import_path, sys_path):
          """
          This method is very similar to importlib's `_gcd_import`.
          """
          import_parts = [
              force_unicode(i.value if isinstance(i, tree.Name) else i)
              for i in import_path
          ]
  
          # Handle "magic" Flask extension imports:
          # ``flask.ext.foo`` is really ``flask_foo`` or ``flaskext.foo``.
          if len(import_path) > 2 and import_parts[:2] == ['flask', 'ext']:
              # New style.
              ipath = ('flask_' + str(import_parts[2]),) + import_path[3:]
              modules = self._do_import(ipath, sys_path)
              if modules:
                  return modules
              else:
                  # Old style
                  return self._do_import(('flaskext',) + import_path[2:], sys_path)
  
          if import_parts[0] in settings.auto_import_modules:
              module = _load_module(
                  self._evaluator,
                  import_names=import_parts,
                  sys_path=sys_path,
              )
              return ContextSet(module)
  
          module_name = '.'.join(import_parts)
          try:
              return ContextSet(self._evaluator.module_cache.get(module_name))
          except KeyError:
              pass
  
          if len(import_path) > 1:
              # This is a recursive way of importing that works great with
              # the module cache.
              bases = self._do_import(import_path[:-1], sys_path)
              if not bases:
                  return NO_CONTEXTS
              # We can take the first element, because only the os special
              # case yields multiple modules, which is not important for
              # further imports.
              parent_module = list(bases)[0]
  
              # This is a huge exception, we follow a nested import
              # ``os.path``, because it's a very important one in Python
              # that is being achieved by messing with ``sys.modules`` in
              # ``os``.
              if import_parts == ['os', 'path']:
                  return parent_module.py__getattribute__('path')
  
              try:
                  method = parent_module.py__path__
              except AttributeError:
                  # The module is not a package.
                  _add_error(self.module_context, import_path[-1])
                  return NO_CONTEXTS
              else:
                  paths = method()
                  debug.dbg('search_module %s in paths %s', module_name, paths)
                  for path in paths:
                      # At the moment we are only using one path. So this is
                      # not important to be correct.
                      if not isinstance(path, list):
                          path = [path]
                      code, module_path, is_pkg = self._evaluator.compiled_subprocess.get_module_info(
                          string=import_parts[-1],
                          path=path,
                          full_name=module_name,
                          is_global_search=False,
                      )
                      if module_path is not None:
                          break
                  else:
                      _add_error(self.module_context, import_path[-1])
                      return NO_CONTEXTS
          else:
              debug.dbg('global search_module %s in %s', import_parts[-1], self.file_path)
              # Override the sys.path. It works only good that way.
              # Injecting the path directly into `find_module` did not work.
              code, module_path, is_pkg = self._evaluator.compiled_subprocess.get_module_info(
                  string=import_parts[-1],
                  full_name=module_name,
                  sys_path=sys_path,
                  is_global_search=True,
              )
              if module_path is None:
                  # The module is not a package.
                  _add_error(self.module_context, import_path[-1])
                  return NO_CONTEXTS
  
          module = _load_module(
              self._evaluator, module_path, code, sys_path,
              import_names=import_parts,
              safe_module_name=True,
          )
  
          if module is None:
              # The file might raise an ImportError e.g. and therefore not be
              # importable.
              return NO_CONTEXTS
  
          return ContextSet(module)
  
      def _generate_name(self, name, in_module=None):
          # Create a pseudo import to be able to follow them.
          if in_module is None:
              return ImportName(self.module_context, name)
          return SubModuleName(in_module, name)
  
      def _get_module_names(self, search_path=None, in_module=None):
          """
          Get the names of all modules in the search_path. This means file names
          and not names defined in the files.
          """
          sub = self._evaluator.compiled_subprocess
  
          names = []
          # add builtin module names
          if search_path is None and in_module is None:
              names += [self._generate_name(name) for name in sub.get_builtin_module_names()]
  
          if search_path is None:
              search_path = self.sys_path_with_modifications()
  
          for name in sub.list_module_names(search_path):
              names.append(self._generate_name(name, in_module=in_module))
          return names
  
      def completion_names(self, evaluator, only_modules=False):
          """
          :param only_modules: Indicates wheter it's possible to import a
              definition that is not defined in a module.
          """
          from jedi.evaluate.context import ModuleContext
          from jedi.evaluate.context.namespace import ImplicitNamespaceContext
          names = []
          if self.import_path:
              # flask
              if self.str_import_path == ('flask', 'ext'):
                  # List Flask extensions like ``flask_foo``
                  for mod in self._get_module_names():
                      modname = mod.string_name
                      if modname.startswith('flask_'):
                          extname = modname[len('flask_'):]
                          names.append(self._generate_name(extname))
                  # Now the old style: ``flaskext.foo``
                  for dir in self.sys_path_with_modifications():
                      flaskext = os.path.join(dir, 'flaskext')
                      if os.path.isdir(flaskext):
                          names += self._get_module_names([flaskext])
  
              for context in self.follow():
                  # Non-modules are not completable.
                  if context.api_type != 'module':  # not a module
                      continue
                  # namespace packages
                  if isinstance(context, ModuleContext) and context.py__file__().endswith('__init__.py'):
                      paths = context.py__path__()
                      names += self._get_module_names(paths, in_module=context)
  
                  # implicit namespace packages
                  elif isinstance(context, ImplicitNamespaceContext):
                      paths = context.paths
                      names += self._get_module_names(paths, in_module=context)
  
                  if only_modules:
                      # In the case of an import like `from x.` we don't need to
                      # add all the variables.
                      if ('os',) == self.str_import_path and not self.level:
                          # os.path is a hardcoded exception, because it's a
                          # ``sys.modules`` modification.
                          names.append(self._generate_name('path', context))
  
                      continue
  
                  for filter in context.get_filters(search_global=False):
                      names += filter.values()
          else:
              # Empty import path=completion after import
              if not self.level:
                  names += self._get_module_names()
  
              if self.file_path is not None:
                  path = os.path.abspath(self.file_path)
                  for i in range(self.level - 1):
                      path = os.path.dirname(path)
                  names += self._get_module_names([path])
  
          return names
  
  
  def _load_module(evaluator, path=None, code=None, sys_path=None,
                   import_names=None, safe_module_name=False):
      if import_names is None:
          dotted_name = None
      else:
          dotted_name = '.'.join(import_names)
      try:
          return evaluator.module_cache.get(dotted_name)
      except KeyError:
          pass
      try:
          return evaluator.module_cache.get_from_path(path)
      except KeyError:
          pass
  
      if isinstance(path, ImplicitNSInfo):
          from jedi.evaluate.context.namespace import ImplicitNamespaceContext
          module = ImplicitNamespaceContext(
              evaluator,
              fullname=path.name,
              paths=path.paths,
          )
      else:
          if sys_path is None:
              sys_path = evaluator.get_sys_path()
  
          if path is not None and path.endswith(('.py', '.zip', '.egg')):
              module_node = evaluator.parse(
                  code=code, path=path, cache=True,
                  diff_cache=settings.fast_parser,
                  cache_path=settings.cache_directory)
  
              from jedi.evaluate.context import ModuleContext
              module = ModuleContext(
                  evaluator, module_node,
                  path=path,
                  code_lines=get_cached_code_lines(evaluator.grammar, path),
              )
          else:
              assert dotted_name is not None
              module = compiled.load_module(evaluator, dotted_name=dotted_name, sys_path=sys_path)
  
      if module is not None and dotted_name is not None:
          add_module_to_cache(evaluator, dotted_name, module, safe=safe_module_name)
  
      return module
  
  
  def add_module_to_cache(evaluator, module_name, module, safe=False):
      if not safe and '.' not in module_name:
          # We cannot add paths with dots, because that would collide with
          # the sepatator dots for nested packages. Therefore we return
          # `__main__` in ModuleWrapper.py__name__(), which is similar to
          # Python behavior.
          return
      evaluator.module_cache.add(module, module_name)
  
  
  def get_modules_containing_name(evaluator, modules, name):
      """
      Search a name in the directories of modules.
      """
      def check_directories(paths):
          for p in paths:
              if p is not None:
                  # We need abspath, because the seetings paths might not already
                  # have been converted to absolute paths.
                  d = os.path.dirname(os.path.abspath(p))
                  for file_name in os.listdir(d):
                      path = os.path.join(d, file_name)
                      if file_name.endswith('.py'):
                          yield path
  
      def check_fs(path):
          try:
              f = open(path, 'rb')
          except FileNotFoundError:
              return
          with f:
              code = python_bytes_to_unicode(f.read(), errors='replace')
              if name in code:
                  e_sys_path = evaluator.get_sys_path()
                  import_names = sys_path.dotted_path_in_sys_path(e_sys_path, path)
                  module = _load_module(
                      evaluator, path, code,
                      sys_path=e_sys_path,
                      import_names=import_names,
                  )
                  return module
  
      # skip non python modules
      used_mod_paths = set()
      for m in modules:
          try:
              path = m.py__file__()
          except AttributeError:
              pass
          else:
              used_mod_paths.add(path)
          yield m
  
      if not settings.dynamic_params_for_other_modules:
          return
  
      additional = set(os.path.abspath(p) for p in settings.additional_dynamic_modules)
      # Check the directories of used modules.
      paths = (additional | set(check_directories(used_mod_paths))) \
              - used_mod_paths
  
      # Sort here to make issues less random.
      for p in sorted(paths):
          # make testing easier, sort it - same results on every interpreter
          m = check_fs(p)
          if m is not None and not isinstance(m, compiled.CompiledObject):
              yield m
  